Resistance mechanism of simple-made-continuous connections in skew and non-skew steel girder bridges using conventional and accelerated types of construction.

摘要

Many analyses show that concrete and pre-stressed concrete bridges tend to be more economical than steel bridges using conventional construction methods. Construction and material cost are two major factors that can affect the total cost of a bridge construction project. Since no control can be taken over material costs, any response must focus on the design and construction methods of steel bridges through reduction of labor and equipment costs. The simple-made-continuous system is one such response. This method can enhance the competitiveness of the short to medium span steel bridges. The simple-made-continuous method causes girder and slab dead loads to be resisted as in a simple span, while the superimposed dead loads and live loads are resisted as in continuous spans.;Three different connections were proposed for the conventional method of construction. Three experimental full scale specimens were conducted to investigate the behavior of the proposed connection during fatigue and ultimate loading. ABAQUS 6.9 was employed to model the experimental specimens to find the resistance mechanism of the connections.;Following successful test results, an accelerated type of connection was proposed as a response to the public demand to reduce on-site construction time and mitigate long traffic delays. This connection was similar to the conventional type connection by modifying the system for the accelerated construction method. In the accelerated construction method, each span is built separately and then connected using the proposed connection to achieve a full continuity during the service life of the structure.;A full scale specimen of a connection using the accelerated method was built in the structural laboratory to investigate the behavior of the specimen. The connection experienced four million cycles during the fatigue test. Following the fatigue test, an ultimate load test was conducted to investigate the failure mechanism of the connection. The experimental tests results are studied to observe the performance of the new connections. A few FEM models are developed to simulate the connections and investigate the load resistance mechanism of the connections in more detail.;Due to the high percentage of skew bridges in the United States, finite element models are developed to investigate the performance of the new connections for skew bridges.;The results of experimental tests and FEM models reveal that longitudinal rebars at top of the diaphragm have the most contribution in the resistance mechanism in tension. Also, steel block, concrete, and connecting plate have the most contribution in the resistance mechanism in compression. In the skew bridges, a lateral force is created from the lateral component of the compression force that can be resisted by the steel plates perpendicular to the lateral force.;By understanding the resistance mechanism of the connections, a design provision is developed to address the design needs for the bridge designer for both non-skew and skew bridges using two different methods of construction.